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PCI-E x8 and x16 issues

Last response: in Graphics & Displays
September 10, 2007 6:29:30 AM

well i bought the 6100m-m motherboard and ive read numerous reviews of it not having full x16 power and only having x8. there was a particular review saying 98% of x16 video cards will not even work on the mobo. is this actually true, or can x16 cards work in the slot just not at full power? i am wondering this because im planning to upgrade from the onboard video to either a GeForce 8600 or Radeon X2600, which i would also like to know, which is a better buy for gaming.
also i dont plan on using a resolution any higher than 1280, if that affects performance much
thanks for any help

More about : pci x16 issues

September 10, 2007 7:41:28 AM

without knowing anything about that specific motherboard, most graphics cards should work with fewer PCI-E lanes. When PCI-E first came out Toms did an article testing 8x, 4x, and 1x by blocking parts of the connector off and at least on... I think it was an X850... it ran fine all the way down to 4x without much of a performance hit. In fact they had more trouble with low-end cards that don't have secondary power connectors because the limited PCI-E bus delivered less power.

September 10, 2007 8:05:30 AM

im not quite sure if that answers the question though. the mobo has a x16 slot, but reviews say that the power of it is only x8 or something like that. id also like to know which is best for current dx9 gaming, x1950 or the 7950 as i dont have vista and dont plan on getting it till the bugs are worked out and dx10 gaming is fully functional
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September 10, 2007 11:02:08 AM

i have ecs gefrce6100sm-m motherboard and i have a geforce 7600Gt installed in the pci-e x16 slot and it works fine in x8 mode.
September 10, 2007 10:33:54 PM

does x8 power affect the performance of a x16 card in any way?
September 10, 2007 10:40:15 PM

Power and Bandwidth are TWO very different issues, a PCI-E x16 slot is able to supply up to 75W regardless of it being set in x8 or x16 I believe, if you're card isn't getting enough power is because it requires an external connection (if your card doesn't have an external plug, then it doesn't require more power than what the slot can provide).

However Bandwidth is a completely different thing, it's basically how much data can travel through the slot, most cards do not have bandwidth issues set on either x8 or x16 (the 8800GTS/GTX might be different, I can't remember but I don't think so), so unless you are considering to get a 8800GTX, you shouldn't worry about the PCIe slot set at x8.

EDIT: The X1950 and 7900/7950 card series all require external power to function properly.
September 10, 2007 10:56:46 PM

so pretty much any PCI-E card(Except 8800) will run fine in the slot then?
also if a card needs more power my PSU has a plug for the card so i guess that wont be a problem
September 10, 2007 10:59:18 PM

Yes, but before you go buying something, what PSU do you have? Just because your PSU has a cable doesn't mean it can supply enough power to the card.
September 10, 2007 11:00:51 PM

umm a 500w antec psu, but your right i am worried that it might not be good enough. either because of brand or not enough watts
September 11, 2007 12:31:08 AM

Antec is a very good PSU maker, however it depends on WHICH antec model you have, because they make something for every customer (Silent PC, Low end, Mainstream, enthusiasts, and extreme users).
September 11, 2007 12:39:31 AM

hmm not sure, but i hope ill be okay with whichever one it is
September 11, 2007 1:32:10 AM

I also have ECS mobo and it alsa says PCI-E x8 so i think its time to change mobo to some other brand.
a b U Graphics card
September 11, 2007 1:51:43 AM

Many motherboards have x8 pathways on an x16 slot, I've never seen a video card that had a problem with that. The 7800GTX and faster cards lose a marginal amount of performance due to the bandwidth limitations, lesser cards don't.